It has previously been known to remove impurities from water and/or wastewater with systems utilizing tube settlers. Tube settlers are most commonly used in bundle configurations. Tube settlers typically measure approximately two feet wide and thirty inches high. Tube settlers are typically oriented on a sixty degree slope to provide the tubes with a developed length of approximately three feet. The length of the bundles of tube settlers range from approximately four feet to fifteen feet. Runs longer than fifteen feet are achieved by orienting multiple bundles in an end-to-end manner. The end-to-end configuration of multiple bundles of tube settlers can provide the tube settler system with an overall length in excess of one hundred feet. Tube settlers are typically formed from PVC or ABS. Tube settlers may be employed in the construction of new systems or in the rehabilitation of existing water and/or wastewater treatment plants.
One of the major deficiencies in previously known tube settlers has been the occurrence of short-circuiting, i.e., the influent flow and effluent flow is not uniformly distributed along the length of the tube settler. Maldistribution results in localized high velocity fluid flow through the tube settlers resulting in significantly reduced settling efficiency. This highly undesirable condition is aggravated when the tubes become clogged with floc resulting in even greater maldistribution of fluid through the tube settlers.
It has previously been proposed to use large distributors below the tube settlers in an effort to avoid maldistribution of fluid through the tube settlers. These distributors are commonly made using large diameter pipes having drilled orifices. These large distributors are expensive. Further, these large distributors occupy considerable space below the tube settlers decreasing the waste collection volume of the vessel in which the tube settlers are located. Similarly, previously developed tube settler systems have employed large collectors to collect the effluent exiting the tube settlers. These effluent collectors include submerged orifices, V-notched weirs or other forms of fluid flow control in an effort to provide even flow above the tube settlers.